1. Field of the Invention
This invention relates to a copier capable of producing an image having two different colors, and particularly to a dual-color electrophotographic copier having an increased number of copy modes.
2. Description of the Prior Art
A copier capable of producing a copy image in an analog format as well as in a digital format is well known in the art. In the analog copy mode, an original to be copied is directly exposed to an imaging surface, such as the surface of a photosensitive member, through an optical system, which generally includes lenses and mirrors, thereby forming an electrostatic latent image on the imaging surface. On the other hand, in the digital copy mode, use is made of a recording head disposed opposite to the imaging surface and including a plurality of pixel forming elements arranged in the form of an array and the pixel forming elements are activated selectively in accordance with an image signal supplied. Thus, there is formed a charge pattern on the imaging surface, which constitutes an electrostatic latent image. Such a copier may be operated in a composite mode, which is a combination of the analog and digital copy modes. In this case, there may be obtained a copy image which is a combination of analog and digital information.
Another prior art copier, which appears to be relevant, is a dual-mode electrophotographic copier which uses a raster scanning mechanism in a dual-mode to carry out image synthesization as disclosed in the Japanese Patent Post-examination Publication, No. 55-47392. However, in this case also, a duplex image is formed on a single photosensitive drum and the manner of forming a variety of copy images is limited.